Vapor growth of typical II-VI wide-gap semiconductor crystals directly from the constituent elements

• ZnE (E = Se,Te) crystals have been grown from vapor directly from constituent elements.
• NH4Cl transport agent produces platelike ZnE crystals, and I2 does conical crystals.
• 3D nucleation mechanism governs ZnSe crystal growth in Zn-Se-I2 system.
• 2D dendrite crystal mechanism dominates ZnE crystal growth in Zn-E-NH4Cl systems.
• The vapor free-growth habits of ZnE crystals have been interpreted well.

Three ZnE (E = Se, Te) single crystals were successfully grown directly from Zn-E (E = Se, Te) system with the assistance of I2 or NH4Cl as the transport agents via a modified chemical vapor transport (CVT) method by avoiding the kinetics limitations of the congruent sublimation of ZnE compound. As-grown ZnE crystals exhibit different crystalline appearance due to various growth conditions. The structure, growth habit and morphologies of as-grown ZnE crystals are investigated by XRD, RO-XRD, SEM and optic microscope. ZnE crystals with NH4Cl transport agent look like the platelets with an interesting growth habit, while ZnE crystal with I2 transport agent has high crystalline quality with a conical shape. Contrasting investigation between different growth results offers us an opportunity to understand the vapor-free-growth mechanism of ZnE crystals in closed-space CVT system, indicating that the free-growth habit of ZnE crystals depends on the growth parameters, which can be essentially attributed to their growth mechanism and the main vapor–solid reactions on the interfaces.

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